Phase change inks comprising crystalline amides

ABSTRACT

A phase change ink composition suitable for high speed ink jet printing, including printing on coated paper substrates. In embodiments, the phase change ink composition comprises both a crystalline compound and an amorphous compound, and optionally, a colorant, which provides for a robust ink. The crystalline compound is an amide and the amorphous compound is an ester of tartaric acid.

CROSS-REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly owned and co-pending, U.S. patentapplication Ser. No. ______ (not yet assigned) entitled “Phase ChangeInk Compositions Comprising Crystalline Diurethanes And DerivativesThereof” to Naveen Chopra et al., electronically filed on the same dayherewith (Attorney Docket No. 20110356-396152); U.S. patent applicationSer. No. ______ (not yet assigned) entitled “Phase change InkCompositions Comprising Crystalline Sulfone Compounds and DerivativesThereof” to Kentaro Morimitsu et al., electronically filed on the sameday herewith (Attorney Docket No. 20110561-396955); U.S. patentapplication Ser. No. ______ (not yet assigned) entitled “Phase ChangeInk Compositions Comprising Aromatic Ethers” to Kentaro Morimitsu etal., electronically filed on the same day herewith (Attorney Docket No.20110362-396157); U.S. patent application Ser. No. ______ (not yetassigned) entitled “Fast Crystallizing Crystalline-Amorphous InkCompositions And Methods For Making The Same” to Gabriel Iftime et al.,electronically filed on the same day herewith (Attorney Docket No.20110459-399389); U.S. patent application Ser. No. ______(not yetassigned) entitled “Rapid Solidify Crystalline-Amorphous Inks” toGabriel Iftime et al., electronically filed on the same day herewith(Attorney Docket No. 20110982-399395);U.S. patent application Ser. No.______ (not yet assigned) entitled “Phase Change Inks ComprisingInorganic Nucleating Agents” to Daryl W. Vanbesien et al.,electronically filed on the same day herewith (Attorney Docket No.20111206-400896); U.S. patent application Ser. No. ______ (not yetassigned) entitled “Phase Change Inks Comprising Fatty Acids” to GabrielIftime et al., electronically filed on the same day herewith (AttorneyDocket No. 20110815-399390); U.S. patent application Ser. No. ______(not yet assigned) entitled “Phase Change Inks Comprising AromaticDiester Crystalline Compounds” to Kentaro Morimitsu et al.,electronically filed on the same day herewith (Attorney Docket No.20111040-399927); U.S. patent application Ser. No. ______ (not yetassigned) entitled “Phase Change Ink Compositions Comprising Diurethanesas Amorphous Materials” to Naveen Chopra et al., electronically filed onthe same day herewith (Attorney Docket No. 20110610-397242); U.S. patentapplication Ser. No. ______ (not yet assigned) entitled “Phase ChangeInks Comprising Organic Pigments” to Jennifer Belelie et al.,electronically filed on the same day herewith (Attorney Docket No.20110418-399388); and U.S. patent application Ser. No. ______ (not yetassigned) entitled “TROM Process for Measuring the Rate ofCrystallization of Phase change Inks” to Gabriel Iftime et al.,electronically filed on the same day herewith (Attorney Docket No.20110828-401275), U.S. patent application Ser. No. ______ (not yetassigned) entitled “Rapidly Crystallizing Phase Change Inks and Methodsfor Forming the Same” to Jennifer Belelie et al., electronically filedon the same day herewith (Attorney Docket No. 20111455-403044); theentire disclosures of which are incorporated herein by reference in itsentirety.

BACKGROUND

The present embodiments relate to phase change ink compositionscharacterized by being solid at room temperature and molten at anelevated temperature at which the molten ink is applied to a substrate.These phase change ink compositions can be used for ink jet printing.The present embodiments are directed to a novel phase change inkcomposition comprising an amorphous compound, a crystalline compound,and optionally a colorant, and methods of making the same. Inparticular, the amorphous compound is an ester of tartaric acid and thecrystalline compound is an amide.

Ink jet printing processes may employ inks that are solid at roomtemperature and liquid at elevated temperatures. Such inks may bereferred to as solid inks, hot melt inks, phase change inks and thelike. For example, U.S. Pat. No. 4,490,731, the disclosure of which istotally incorporated herein by reference, discloses an apparatus fordispensing phase change ink for printing on a recording medium such aspaper. In piezo ink jet printing processes employing hot melt inks, thephase change ink is melted by the heater in the printing apparatus andutilized (jetted) as a liquid in a manner similar to that ofconventional piezo ink jet printing. Upon contact with the printingrecording medium, the molten ink solidifies rapidly, enabling thecolorant to substantially remain on the surface of the recording mediuminstead of being carried into the recording medium (for example, paper)by capillary action, thereby enabling higher print density than isgenerally obtained with liquid inks. Advantages of a phase change ink inink jet printing are thus elimination of potential spillage of the inkduring handling, a wide range of print density and quality, minimalpaper cockle or distortion, and enablement of indefinite periods ofnonprinting without the danger of nozzle clogging, even without cappingthe nozzles.

In general, phase change inks (sometimes referred to as “hot melt inks”)are in the solid phase at ambient temperature, but exist in the liquidphase at the elevated operating temperature of an ink jet printingdevice. At the jetting temperature, droplets of liquid ink are ejectedfrom the printing device and, when the ink droplets contact the surfaceof the recording medium, either directly or via an intermediate heatedtransfer belt or drum, they quickly solidify to form a predeterminedpattern of solidified ink drops.

Phase change inks for color printing typically comprise a phase changeink carrier composition which is combined with a phase change inkcompatible colorant. In a specific embodiment, a series of colored phasechange inks can be formed by combining ink carrier compositions withcompatible subtractive primary colorants. The subtractive primarycolored phase change inks can comprise four component dyes or pigments,namely, cyan, magenta, yellow and black, although the inks are notlimited to these four colors. These subtractive primary colored inks canbe formed by using a single dye or pigment or a mixture of dyes orpigments. For example, magenta can be obtained by using a mixture ofSolvent Red Dyes or a composite black can be obtained by mixing severaldyes. U.S. Pat. No. 4,889,560, U.S. Pat. No. 4,889,761, and U.S. Pat.No. 5,372,852, the disclosures of each of which are totally incorporatedherein by reference, teach that the subtractive primary colorantsemployed can comprise dyes from the classes of Color Index (C.I.)Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and BasicDyes. The colorants can also include pigments, as disclosed in, forexample, U.S. Pat. No. 5,221,335, the disclosure of which is totallyincorporated herein by reference. U.S. Pat. No. 5,621,022, thedisclosure of which is totally incorporated herein by reference,discloses the use of a specific class of polymeric dyes in phase changeink compositions.

Phase change inks are desirable for ink jet printers because they remainin a solid phase at room temperature during shipping, long term storage,and the like. In addition, the problems associated with nozzle cloggingas a result of ink evaporation with liquid ink jet inks are largelyeliminated, thereby improving the reliability of the ink jet printing.Further, in phase change ink jet printers wherein the ink droplets areapplied directly onto the final recording medium (for example, paper,transparency material, and the like), the droplets solidify immediatelyupon contact with the recording medium, so that migration of ink alongthe printing medium is prevented and dot quality is improved.

While the above conventional phase change ink technology is generallysuccessful in producing vivid images and providing economy of jet useand substrate latitude on porous papers, such technology has not beensatisfactory for coated substrates. Thus, while known compositions andprocesses are suitable for their intended purposes, a need remains foradditional means for forming images or printing on coated papersubstrates. As such, there is a need to find alternative compositionsfor phase change ink compositions and future printing technologies toprovide customers with excellent image quality on all substrates,including selecting and identifying different classes of materials thatare suitable for use as desirable ink components.

There is further a need to provide such phase change ink compositionswhich are suitable for fast printing environments like productionprinting.

Each of the foregoing U.S. patents and patent publications areincorporated by reference herein. Further, the appropriate componentsand process aspects of the each of the foregoing U.S. patents and patentpublications may be selected for the present disclosure in embodimentsthereof.

SUMMARY

According to embodiments illustrated herein, there is provided novelphase change ink compositions comprising crystalline amide and amorphousesters of tartaric acid for ink jet printing, including printing oncoated paper substrates.

In particular, the present embodiments provide a phase change inkcomprising an amorphous compound; and a crystalline compound being anamide having a formula of:

wherein each R₃ and R₄ is independently selected from the groupconsisting of (i) an alkyl group, which can be a linear or branched,cyclic or acyclic, substituted or unsubstituted, saturated orunsaturated, alkyl group, and wherein heteroatoms may optionally bepresent in the alkyl group having from about 1 to about 40 carbon atoms;(ii) an arylalkyl group, which can be a substituted or unsubstitutedarylalkyl group, wherein the alkyl portion of arylalkyl group can belinear or branched, cyclic or acyclic, substituted or unsubstituted,saturated or unsaturated, and wherein heteroatoms may optionally bepresent in either the aryl portion or the alkyl portion of the arylalkylgroup having from about 4 to about 40 carbon atoms; and (iii) anaromatic group, which can be a substituted or unsubstituted aromaticgroup wherein the substituent can be a linear, branched, cyclic oracyclic alkyl group and, wherein heteroatoms may optionally be presentin the aromatic group having from about 3 to about 40 carbon atoms, andmixtures thereof; and wherein the phase change ink crystallizes in lessthan 15 seconds.

In further embodiments, there is provided a phase change ink comprisingan amorphous compound comprises an ester of tartaric acid of Formula I

wherein each R₁ and R₂ is independently an alkyl group, wherein thealkyl can be straight, branched or cyclic, saturated or unsaturated,substituted or unsubstituted, having from about 1 to about 40 carbonatoms, or an substituted or unsubstituted aromatic or heteroaromaticgroup, and mixtures thereof; and further wherein the tartaric acidbackbone is selected from L-(+)-tartaric acid, D-(−) -tartaric acid,DL-tartaric acid, or mesotartaric acid, and mixtures thereof; and acrystalline compound being an amide having the following structure:

wherein each R₃ and R₄ is independently selected from the groupconsisting of (i) an alkyl group, which can be a linear or branched,cyclic or acyclic, substituted or unsubstituted, saturated orunsaturated, alkyl group, and wherein heteroatoms may optionally bepresent in the alkyl group having from about 1 to about 40 carbon atoms;(ii) an arylalkyl group, which can be a substituted or unsubstitutedarylalkyl group, wherein the alkyl portion of arylalkyl group can belinear or branched, cyclic or acyclic, substituted or unsubstituted,saturated or unsaturated, and wherein heteroatoms may optionally bepresent in either the aryl portion or the alkyl portion of the arylalkylgroup having from about 4 to about 40 carbon atoms; and (iii) anaromatic group, which can be a substituted or unsubstituted aromaticgroup wherein the substituent can be a linear, branched, cyclic oracyclic alkyl group and, wherein heteroatoms may optionally be presentin the aromatic group having from about 3 to about 40 carbon atoms, andmixtures thereof; and further wherein the phase change ink has aT_(melt) of from about 65 to about 140° C. and a T_(crys) of from about40 to about 140° C.

In yet other embodiments, there is provided a phase change inkcomprising an amorphous compound; and a crystalline compound, whereinthe amorphous compound is an ester of tartaric acid and is synthesizedby an esterification reaction with at least one alcohol, and thecrystalline compound is an amide having the following structure:

wherein each R₅ and R₆ is independently aryl, or heteroaryl, optionallysubstituted with one or more alkyl, alkoxy, —NH₂, —CN, or —OH; m is from0 to 6, n is from 0 to 6.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present embodiments, reference may behad to the accompanying figures.

FIG. 1 is a graph illustrating rheology data of tri-DL-menthyl citrate(TMC) and di-DL-menthyl L-tartrate (DMT) used as amorphous compounds;

FIG. 2 illustrates the TROM process showing images of crystallineformation in an ink base from crystallization onset to crystallizationcompletion according to an embodiment of the disclosure.

FIG. 3 is differential scanning calorimetry (DSC) data of an ink basecomprising N-phenethylbenzamide according to the present embodiments(the DSC data was obtained on a Q1000 Differential Scanning calorimeter(TA Instruments) at a rate of 10° C./min from −50 to 200 to −50° C.);

FIG. 4 is DSC data of a sample ink made with the ink base of FIG. 3 anddye according to the present embodiments; and

FIG. 5 is a graph illustrating rheology data of the ink base of FIG. 3and the ink sample of FIG. 4 according to the present embodiments.

All of the rheology measurements were made on a RFS3 controlled strainRheometer (TA instruments) equipped with a Peltier heating plate andusing a 25 mm parallel plate. The method used was a temperature sweepfrom high to low temperatures, in temperature steps of 5° C., a soak(equilibration) time of 120 seconds between each temperature and at aconstant frequency of 1 Hz.

DETAILED DESCRIPTION

In the following description, it is understood that other embodimentsmay be utilized and structural and operational changes may be madewithout departure from the scope of the present embodiments disclosedherein.

As used herein, the term “alkyl” refers to an aliphatic hydrocarbongroup. The alkyl moiety may be a “saturated alkyl” group, which meansthat it does not contain any alkene or alkyne moieties. The alkyl moietymay also be an “unsaturated alkyl” moiety, which means that it containsat least one alkene or alkyne moiety. An “alkene” moiety refers to agroup consisting of at least two carbon atoms and at least onecarbon-carbon double bond, and an “alkyne” moiety refers to a groupconsisting of at least two carbon atoms and at least one carbon-carbontriple bond. The alkyl moiety, whether saturated or unsaturated, may bebranched, straight chain, or cyclic.

The alkyl group may have 1 to 40 carbon atoms (whenever it appearsherein, a numerical range such as “1 to 40” refers to each integer inthe given range; e.g., “1 to 40 carbon atoms” means that the alkyl groupmay consist of 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., upto and including 40 carbon atoms, although the present definition alsocovers the occurrence of the term “alkyl” where no numerical range isdesignated). The alkyl group may also be a medium size alkyl having 1 to10 carbon atoms. The alkyl group could also be a lower alkyl having 1 to4 carbon atoms. The alkyl group of the compounds of the invention may bedesignated as “C₁-C₄ alkyl” or similar designations. By way of exampleonly, “C₁-C₄ alkyl” indicates that there are one to four carbon atoms inthe alkyl chain, i.e., the alkyl chain is selected from the groupconsisting of methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl,sec-butyl, and t-butyl.

The alkyl group may be substituted or unsubstituted. When substituted,any group(s) besides hydrogen can be the substitutent group(s). Whensubstituted, the substituent group(s) is(are) one or more group(s)individually and independently selected from the following non-limitingillustrative list: alkyl, cycloalkyl, hydroxy, alkoxy, cyano, halo, andamino, including mono- and di-substituted amino groups. Typical alkylgroups include, but are in no way limited to, methyl, ethyl, propyl,isopropyl, butyl, isobutyl, tertiary butyl, pentyl, hexyl, ethenyl,propenyl, butenyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, andthe like. Each substituent group may be further substituted.

The term “aryl,” as used herein, alone or in combination, means acarbocyclic aromatic system containing one, two or three rings whereinsuch rings may be attached together in a pendent manner or may be fused.The term “aryl,” embraces aromatic radicals such as benzyl, phenyl,naphthyl, anthracenyl, and biphenyl.

The term “arylalkyl” as used herein, alone or in combination, refers toan aryl group attached to the parent molecular moiety through an alkylgroup.

Phase change ink technology broadens printing capability and customerbase across many markets, and the diversity of printing applicationswill be facilitated by effective integration of printhead technology,print process and ink materials. The phase change ink compositions arecharacterized by being solid at room temperature (RT) (e.g., 20-27° C.)and molten at an elevated temperature at which the molten ink is appliedto a substrate. As discussed above, while current ink options aresuccessful for porous paper substrates, these options are not alwayssatisfactory for coated paper substrates.

It was previously discovered that using a mixture of crystalline andamorphous small molecule compounds in solid ink formulations providesrobust inks, and in particular, solid inks which demonstrate robustimages on coated paper. (U.S. patent application Ser. No. 13/095,636entitled “Solid Ink Compositions Comprising Crystalline-AmorphousMixtures” to Jennifer L. Belelie et al., (Attorney Docket No.20101286-390681) filed Apr. 27, 2011. Print samples made with such phasechange inks demonstrate better robustness with respect to scratch, fold,and fold offset as compared to currently available phase change inks.

However, the present inventors discovered that in many cases mixturesmade of crystalline and amorphous materials with optional dye colorantsolidify slowly when printed on substrates from a molten state. Suchslow solidifying inks are not suitable for high speed printingenvironments, like for example production printing, where printing atspeeds higher than 100 feet per minute is required. Solidification ofthe ink is due to crystallization of the crystalline component in theink when cooling.

The inventors have found that fast crystallization of a composition madeof a crystalline and an amorphous component is not an inherent propertyof the composition.

The present embodiments provide novel phase change ink compositionscomprising crystalline amide materials and amorphous materials whichcrystallize fast and are therefore suitable for high speed ink jetprinting, including printing on coated paper.

The present embodiments provide a new type of ink jet phase change inkcomposition which comprises a blend of (1) crystalline and (2) amorphouscompounds, generally in a weight ratio of from about 60:40 to about95:5, respectively. In more specific embodiments, the weight ratio ofthe crystalline to amorphous compound is from about 65:35 to about 95:5,or is from about 70:30 to about 90:10, or is from about 70:30 to about80:20.

Each compound or component imparts specific properties to the phasechange inks, and the resulting inks incorporating a blend of theseamorphous and crystalline compounds demonstrate excellent robustness onuncoated and coated substrates. The crystalline compound in the inkformulation drives the phase change through rapid crystallization oncooling. The crystalline compound also sets up the structure of thefinal ink film and creates a hard ink by reducing the tackiness of theamorphous compound. The amorphous compounds provide tackiness and impartrobustness to the printed ink.

The Amorphous Compound

Generally, the amorphous compound is comprises an ester of tartaric acidof Formula I

wherein each R₁ and R₂, is independently an alkyl group, wherein thealkyl can be straight, branched or cyclic, saturated or unsaturated,substituted or unsubstituted, having from about 1 to about 40 carbonatoms, or an substituted or unsubstituted aromatic or heteroaromaticgroup, and mixtures thereof. In certain embodiments, each R₁ and R₂ isindependently a cyclohexyl group optionally substituted with one or morealkyl group(s) selected from methyl, ethyl, n-propyl, isopropyl, n-butyland t-butyl. In certain embodiments, R₁ and R₂ are each2-isopropyl-5-methylcyclohexyl.

Referring to Formula I, in certain embodiments, one of R₁ and R₂ is2-isopropyl-5-methylcyclohexyl, and the other one of R₁ and R₂ is2-isopropyl-5-methylcyclohexyl, 4-t-butylcyclohexyl, or cyclohexyl, orone of R₁ and R₂ is 4-t-butylcyclohexyl, and the other one of R₁ and R₂is cyclohexyl. In certain embodiment, R₁ and R₂ are each2-isopropyl-5-methylcyclohexyl. In certain embodiment, R₁ is2-isopropyl-5-methylcyclohexyl and R₂ is 4-t-butylcyclohexyl. In certainembodiment, R₁ is 2-isopropyl-5-methylcyclohexyl and R₂ is cyclohexyl.In certain embodiment, R₁ is 4-t-butylcyclohexyl and R₂ is cyclohexyl.

Referring to Formula II, in certain embodiments, one of R₃, R₄ and R₅ is2-isopropyl-5-methylcyclohexyl, and the other one of R₃, R₄ and R₅ is2-isopropyl-5-methylcyclohexyl, 4-t-butylcyclohexyl, or cyclohexyl, orone of R₃, R₄ and R₅ is 4-t-butylcyclohexyl, and the other one of R₃, R₄and R₅ is cyclohexyl. In certain embodiment, R₃, R₄ and R₅ are each2-isopropyl-5-methylcyclohexyl. In certain embodiment, R₃ is2-isopropyl-5-methylcyclohexyl and R₄ and R₅ are each4-t-butylcyclohexyl. In certain embodiment, R₃ is2-isopropyl-5-methylcyclohexyl and R₄ and R₅ are each cyclohexyl. Incertain embodiment, R₃ is 4-t-butylcyclohexyl and R₄ and R₅ are eachcyclohexyl.

The tartaric acid backbone is selected from L-(+)-tartaric acid,D-(−)-tartaric acid, DL-tartaric acid, or mesotartaric acid, andmixtures thereof. Depending on the R groups and the stereochemistries oftartaric acid, the esters could form crystals or stable amorphouscompounds. In specific embodiments, the amorphous compound is selectedfrom the group consisting of di-L-menthyl L-tartrate, di-DL-menthylL-tartrate (DMT), di-L-menthyl DL-tartrate, di-DL-menthyl DL-tartrate,and any stereoisomers and mixtures thereof.

In particular, di-DL-menthyl L-tartrate (DMT) was found to be especiallysuitable for use as an amorphous compound in the present inkembodiments. Previous compounds found to be suitable for the amorphouscomponent of the ink were esters of citric acid, as disclosed in U.S.patent application Ser. No. 13/095,770 filed on Apr. 27, 2011, which ishereby incorporated by reference in its entirety. In that application,an amorphous tri-DL-menthyl citrate (TMC) was tested and demonstratedrobust printing on a coated substrate. TMC is a desirable amorphouscandidate which affords suitable thermal and rheological properties aswell imparts robustness to the print images. Upon further materialsscreening, DMT was shown to be a promising amorphous material havingsimilar properties to TMC, as shown in FIG. 1.

To synthesize the amorphous component, tartaric acid was reacted with avariety of alcohols to make di-esters as shown in the synthesis schemeshown in U.S. patent application Ser. No. 13/095,784. Suitable alcoholsto be used with the present embodiments may be selected from the groupconsisting of alkyl alcohol, wherein the alkyl portion of the alcoholcan be straight, branched or cyclic, saturated or unsaturated,substituted or unsubstituted, having from about 1 to about 40 carbonatoms, or a substituted or unsubstituted aromatic or heteroaromaticgroup, and mixtures thereof. A variety of alcohols may be used in theesterification such as, for example, menthol, isomenthol, neomenthol,isoneomenthol and any stereoisomers and mixtures thereof. Mixtures ofaliphatic alcohols may be used in the esterification. Suitable alcoholsused in mixed reactions include cyclohexanol and substitutedcyclohexanols (e.g., 2, 3 or 4-t-Butyl cyclohexanol). For example, amixture of two aliphatic alcohols may be used in the esterification. Themolar ratios of the aliphatic alcohols may be from 25:75 to 75:25, from40:60 to 60:40, or about 50:50.

In embodiments, two or more molar equivalents of alcohol may be used inthe reaction to produce the di-esters of tartaric acid. If one molarequivalent of alcohol is used, the result is mostly mono-esters.

The amorphous compounds are synthesized by an esterification reaction oftartaric acid. These materials show relatively low viscosity (<10²centipoise (cps), or from about 1 to about 100 cps, or from about 5 toabout 95 cps) near the jetting temperature (≦140° C., or from about 100to about 140° C., or from about 105 to about 140° C.) but very highviscosity (>10⁵ cps) at room temperature.

In embodiments, the amorphous compounds are formulated with acrystalline compound to form a phase change ink composition. The inkcompositions show good rheological profiles. Print samples created bythe phase change ink composition on coated paper by K-proof exhibitexcellent robustness. Furthermore, using tartaric acid as an ester basehas additional advantages of being derived from a potential bio-derivedsource.

In embodiments, the phase change ink composition is obtained by usingamorphous compounds synthesized from tartaric acid and at least onealcohol in an esterification reaction. The phase change ink compositioncomprises the amorphous compound in combination with a crystallinecompound and a colorant. The present embodiments comprise a balance ofamorphous and crystalline compounds to realize a sharp phase transitionfrom liquid to solid and facilitate hard and robust printed images,while maintaining a desired level of viscosity. Prints made with thisink demonstrated advantages over commercially available inks, such asfor example, better robustness against scratch. Thus, the present estersof tartaric acid, which provide amorphous compounds for the phase changeinks, have been discovered to produce robust inks having desirablerheological profiles and that meet the many requirements for inkjetprinting.

The Crystalline Compound

Generally, the crystalline compound has the following structure:

wherein R₃ and R₄ can be the same or different, each R₃ and R₄ isindependently selected from the group consisting of (i) an alkyl group,which can be a linear or branched, cyclic or acyclic, substituted orunsubstituted, saturated or unsaturated, alkyl group, and whereinheteroatoms may optionally be present in the alkyl group, inembodiments, having from about 1 to about 40 carbon atoms, from about 1to about 20 carbon atoms, or from about 1 to about 10 carbon atoms, (ii)an arylalkyl group, which can be a substituted or unsubstitutedarylalkyl group, wherein the alkyl portion of arylalkyl group can belinear or branched, cyclic or acyclic, substituted or unsubstituted,saturated or unsaturated, and wherein heteroatoms may optionally bepresent in either the aryl portion or the alkyl portion of the arylalkylgroup, in embodiments, having from about 4 to about 40 carbon atoms,from about 7 to about 20 carbon atoms, or from about 7 to about 12carbon atoms and (iii) an aromatic group, which can be a substituted orunsubstituted aromatic group wherein the substituent can be a linear,branched, cyclic or acyclic alkyl group and, wherein heteroatoms mayoptionally be present in the aromatic group, having from about 3 toabout 40 carbon atoms, from about 6 to about 20 carbon atoms, or fromabout 6 to about 10 carbon atoms.

In certain embodiments, the crystalline compound has the followingstructure:

wherein each R₅ and R₆ is independently aryl, or heteroaryl, optionallysubstituted with one or more alkyl, alkoxy, —NH₂, —CN, or —OH; m is from0 to 6, n is from 0 to 6. In certain embodiments, each R₅ and R₆ isindependently phenyl or naphthyl, optionally substituted with one ormore methyl, ethyl, methoxy, ethoxy, —NH₂, —CN, or —OH. In certainembodiments, each R₅ and R₆ is phenyl. In certain embodiments, m is from0 to 2. In certain embodiments, n is from 0 to 2. In certainembodiments, each R₅ and R₆ is an optionally substituted phenyl.

In certain embodiments, R₃ is —(CH₂)_(m)—R₅, wherein aryl, orheteroaryl, optionally substituted with one or more alkyl, alkoxy, —NH₂,—CN, or —OH; and m is from 0 to 6.

In certain embodiments, R₄ is —(CH₂)_(m)—R₆, wherein aryl, orheteroaryl, optionally substituted with one or more alkyl, alkoxy, —NH₂,—CN, or —OH; and n is from 0 to 6.

For the aromatic amides, three specific candidates were selected forexperimental data: N-phenethylhydrocinnamide, N-phenethylbenzamide, andN-benzylbenzamide. The synthesis of N-phenethylhydrocinnamide andN-phenethylbenzamide are described in U.S. patent application Ser. No.13/095,770. N-benzylbenzamide was purchased from Sigma-Aldrich (St.Louis, Mo.).

All of the materials exhibited very sharp transitions within thedesirable temperature range, as shown by the thermal propertiesdescribed in Table 1. This data indicates that the materials havedesirable properties for the phase changing material of the ink. Therelatively narrow gap between melting temperature (T_(melt)) andcrystallization temperature (T_(crys)) translates to a rapid phasechange, making these materials especially good candidates for thecrystalline compound of the ink.

TABLE 1 Amide T_(melt)-T_(crys) Miscibility No. Structure T_(melt) (°C.)* T_(crys) (° C.)* (° C.) with DMT 1

98 71 27 Miscible 2

117 100 17 Miscible 3

106 69 37 Miscible *The DSC data was obtained on a Q1000 DifferentialScanning Calorimeter (TA Instruments) at a rate of 10° C./min from −50to 200 to −50° C.

In certain embodiments, the crystalline materials are from a class ofaromatic amide compounds which were shown to be miscible with anamorphous material. Aromatic amides are known in literature andavailable from commercial sources, however, their properties varydepending on chemical structure. The present embodiments use selectedaromatic amides as the crystalline compound to provide desirableproperties for phase change inks. The crystalline materials show sharpcrystallization, relatively low viscosity (≦10¹ centipoise (cps), orfrom about 0.5 to about 20 cps, or from about 1 to about 15 cps) at atemperature of about 140° C., but very high viscosity (>10⁶ cps) at roomtemperature. These materials have a melting temperature (T_(melt)) ofless than 150° C., or from about 65 to about 150° C., or from about 66to about 145° C., and a crystallization temperature (T_(crys)) ofgreater than 60° C., or from about 60 to about 140° C., or from about 65to about 120° C. The ΔT between T_(melt) and T_(crys) is less than about55° C.

These properties demonstrate that these aromatic amides are well-suitedfor acting as the crystalline compound of the phase change ink of thepresent embodiments.

In the present embodiments, the phase change ink composition may alsocomprise the crystalline and amorphous material in combination with acolorant. The present embodiments comprise a balance of amorphous andcrystalline materials to realize a sharp phase transition from liquid tosolid and facilitate hard and robust printed images, while maintaining adesired level of viscosity. Prints made with this ink demonstratedadvantages over commercially available inks, such as for example, betterrobustness against scratch. Thus, the resulting ink compositionscomprising a blend of the crystalline and amorphous compounds showdesirable rheological profiles and that meet the many requirements forink jet printing.

The ink composition, in specific embodiments, comprises a colorant,which may be a pigment or dye, present in the ink composition in anamount of at least from about 0.1 percent to about 50 percent by weight,or at least from about 0.2 percent to about 20 percent by weight, orfrom about 0.5 percent to about 10 percent by weight of the total weightof the ink composition. In embodiments, the crystalline material ispresent an amount of from about 60 percent to about 95 percent byweight, or from about 65 percent to about 95 percent by weight, or fromabout 70 percent to about 90 percent by weight of the total weight ofthe ink composition. In embodiments, the amorphous material is presentin an amount of from about 5 percent to about 40 percent by weight, orfrom about 5 percent to about 35 percent by weight, or from about 10percent to about 30 percent by weight of the total weight of the inkcomposition.

In embodiments, in the molten state, the resulting solid ink has aviscosity of from about 1 to about 22 cps, or from about 4 to about 15cps, or from about 6 to about 12 cps, at a the jetting temperature. Thejetting temperature is typically comprised in a range from about 100° C.to about 140° C. In embodiments, the solid ink has a viscosity of about>10⁵ cps, at room temperature. In embodiments, the solid ink has aT_(melt) of from about 65 to about 140° C. from about 80 to about 135°C. and a T_(crys) of from about 40 to about 140° C., or from about 45 toabout 130° C., from about 50 to about 120° C., as determined by DSC at arate of 10° C./min.

The ink of embodiments may further include conventional additives totake advantage of the known functionality associated with suchconventional additives. Such additives may include, for example, atleast one antioxidant, defoamer, slip and leveling agents, clarifier,viscosity modifier, adhesive, plasticizer and the like.

The ink may optionally contain antioxidants to protect the images fromoxidation and also may protect the ink components from oxidation whileexisting as a heated melt in the ink reservoir. Examples of suitableantioxidants include N,N′-hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide) (IRGANOX 1098, available from BASF),2,2-bis(4-(2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy))ethoxyphenyl)propane (TOPANOL-205, available from Vertullus),tris(4-tert-butyl-3-hydroxy-2,6-dimethyl benzyl)isocyanurate (Aldrich),2,2′-ethylidene bis(4,6-di-tert-butylphenyl)fluoro phosphonite(ETHANOX-398, available from Albermarle Corporation),tetrakis(2,4-di-tert-butylphenyl)-4,4′-biphenyl diphosphonite (Aldrich),pentaerythritol tetrastearate (TCI America), tributylammoniumhypophosphite (Aldrich), 2,6-di-tert-butyl-4-methoxyphenol (Aldrich),2,4-di-tert-butyl-6-(4-methoxybenzyl)phenol (Aldrich),4-bromo-2,6-dimethylphenol (Aldrich), 4-bromo-3,5-didimethylphenol(Aldrich), 4-bromo-2-nitrophenol (Aldrich), 4-(diethylaminomethyl)-2,5-dimethylphenol (Aldrich), 3-dimethylaminophenol(Aldrich), 2-amino-4-tert-amylphenol (Aldrich),2,6-bis(hydroxymethyl)-p-cresol (Aldrich), 2,2′-methylenediphenol(Aldrich), 5-(diethylamino)-2-nitrosophenol (Aldrich),2,6-dichloro-4-fluorophenol (Aldrich), 2,6-dibromo fluoro phenol(Aldrich), α-trifluoro-o-creso-1 (Aldrich), 2-bromo-4-fluorophenol(Aldrich), 4-fluorophenol (Aldrich),4-chlorophenyl-2-chloro-1,1,2-tri-fluoroethyl sulfone (Aldrich),3,4-difluoro phenylacetic acid (Adrich), 3-fluorophenylacetic acid(Aldrich), 3,5-difluoro phenylacetic acid (Aldrich),2-fluorophenylacetic acid (Aldrich), 2,5-bis(trifluoromethyl) benzoicacid (Aldrich),ethyl-2-(4-(4-(trifluoromethyl)phenoxy)phenoxy)propionate (Aldrich),tetrakis (2,4-di-tert-butyl phenyl)-4,4′-biphenyl diphosphonite(Aldrich), 4-tert-amyl phenol (Aldrich),3-(2H-benzotriazol-2-yl)-4-hydroxy phenethylalcohol (Aldrich), NAUGARD76, NAUGARD 445, NAUGARD 512, AND NAUGARD 524 (manufactured by ChemturaCorporation), and the like, as well as mixtures thereof. Theantioxidant, when present, may be present in the ink in any desired oreffective amount, such as from about 0.25 percent to about 10 percent byweight of the ink or from about 1 percent to about 5 percent by weightof the ink.

In embodiments, the phase change ink compositions described herein alsoinclude a colorant. The ink of the present embodiments can thus be onewith or without colorants. Any desired or effective colorant can beemployed in the phase change ink compositions, including dyes, pigments,mixtures thereof, and the like, provided that the colorant can bedissolved or dispersed in the ink carrier. Any dye or pigment may bechosen, provided that it is capable of being dispersed or dissolved inthe ink carrier and is compatible with the other ink components. Thephase change carrier compositions can be used in combination withconventional phase change ink colorant materials, such as Color Index(C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, BasicDyes, Sulphur Dyes, Vat Dyes, and the like. Examples of suitable dyesinclude Neozapon Red 492 (BASF); Orasol Red G (Pylam Products); DirectBrilliant Pink B (Oriental Giant Dyes); Direct Red 3BL (ClassicDyestuffs); Supranol Brilliant Red 3BW (Bayer AG); Lemon Yellow 6G(United Chemie); Light Fast Yellow 3G (Shaanxi); Aizen Spilon YellowC-GNH (Hodogaya Chemical); Bemachrome Yellow GD Sub (Classic Dyestuffs);Cartasol Brilliant Yellow 4GF (Clariant); Cibanone Yellow 2G (ClassicDyestuffs); Orasol Black RLI (BASF); Orasol Black CN (Pylam Products);Savinyl Black RLSN(Clariant); Pyrazol Black BG (Clariant); Morfast Black101 (Rohm & Haas); Diaazol Black RN (101); Thermoplast Blue 670 (BASF);Orasol Blue GN (Pylam Products); Savinyl Blue GLS (Clariant); Luxol FastBlue MBSN (Pylam Products); Sevron Blue 5GMF (Classic Dyestuffs);Basacid Blue 750 (BASF); Keyplast Blue (Keystone Aniline Corporation);Neozapon Black X51 (BASF); Classic Solvent Black 7 (Classic Dyestuffs);Sudan Blue 670 (CA. 61554) (BASF); Sudan Yellow 146 (C.I. 12700) (BASF);Sudan Red 462 (C.I. 26050) (BASF); C.I. Disperse Yellow 238; Neptune RedBase NB543 (BASF, C.I. Solvent Red 49); Neopen Blue FF-4012 (BASF);Lampronol Black BR (C.I. Solvent Black 35) (101); Morton Morplas Magenta36 (C.I. Solvent Red 172); metal phthalocyanine colorants such as thosedisclosed in U.S. Pat. No. 6,221,137, the disclosure of which is totallyincorporated herein by reference, and the like. Polymeric dyes can alsobe used, such as those disclosed in, for example, U.S. Pat. No.5,621,022 and U.S. Pat. No. 5,231,135, the disclosures of each of whichare herein entirely incorporated herein by reference, and commerciallyavailable from, for example, Milliken & Company as Milliken Ink Yellow869, Milliken Ink Blue 92, Milliken Ink Red 357, Milliken Ink Yellow1800, Milliken Ink Black 8915-67, uncut Reactint Orange X-38, uncutReactint Blue X-17, Solvent Yellow 162, Acid Red 52, Solvent Blue 44,and uncut Reactint Violet X-80.

Pigments are also suitable colorants for the phase change inks. Examplesof suitable pigments include PALIOGEN Violet 5100 (BASF); PALIOGENViolet 5890 (BASF); HELIOGEN Green L8730 (BASF); LITHOL Scarlet D3700(BASF); SUNFAST Blue 15:4 (Sun Chemical); Hostaperm Blue B2G-D(Clariant); Hostaperm Blue B4G (Clariant); Permanent Red P-F7RK;Hostaperm Violet BL (Clariant); LITHOL Scarlet 4440 (BASF); Bon Red C(Dominion Color Company); ORACET Pink RF (BASF); PALIOGEN Red 3871 K(BASF); SUNFAST Blue 15:3 (Sun Chemical); PALIOGEN Red 3340 (BASF);SUNFAST Carbazole Violet 23 (Sun Chemical); LITHOL Fast Scarlet L4300(BASF); SUNBRITE Yellow 17 (Sun Chemical); HELIOGEN Blue L6900, L7020(BASF); SUNBRITE Yellow 74 (Sun Chemical); SPECTRA PAC C Orange 16 (SunChemical); HELIOGEN Blue K6902, K6910 (BASF); SUNFAST Magenta 122 (SunChemical); HELIOGEN Blue D6840, D7080 (BASF); Sudan Blue OS (BASF);NEOPEN Blue FF4012 (BASF); PV Fast Blue B2GO1 (Clariant); IRGALITE BlueGLO (BASF); PALIOGEN Blue 6470 (BASF); Sudan Orange G (Aldrich), SudanOrange 220 (BASF); PALIOGEN Orange 3040 (BASF); PALIOGEN Yellow 152,1560 (BASF); LITHOL Fast Yellow 0991 K (BASF); PALIOTOL Yellow 1840(BASF); NOVOPERM Yellow FGL (Clariant); Ink Jet Yellow 4G VP2532(Clariant); Toner Yellow HG (Clariant); Lumogen Yellow D0790 (BASF);Suco-Yellow L1250 (BASF); Suco-Yellow D1355 (BASF); Suco Fast YellowD1355, D1351 (BASF); HOSTAPERM Pink E 02 (Clariant); Hansa BrilliantYellow 5GX03 (Clariant); Permanent Yellow GRL 02 (Clariant); PermanentRubine L6B 05 (Clariant); FANAL Pink D4830 (BASF); CINQUASIA Magenta (DUPONT); PALIOGEN Black L0084 (BASF); Pigment Black K801 (BASF); andcarbon blacks such as REGAL 330™ (Cabot), Nipex 150 (Evonik) CarbonBlack 5250 and Carbon Black 5750 (Columbia Chemical), and the like, aswell as mixtures thereof.

Pigment dispersions in the ink base may be stabilized by synergists anddispersants. Generally, suitable pigments may be organic materials orinorganic.

Also suitable are the colorants disclosed in U.S. Pat. No. 6,472,523,U.S. Pat. No. 6,726,755, U.S. Pat. No. 6,476,219, U.S. Pat. No.6,576,747, U.S. Pat. No. 6,713,614, U.S. Pat. No. 6,663,703, U.S. Pat.No. 6,755,902, U.S. Pat. No. 6,590,082, U.S. Pat. No. 6,696,552, U.S.Pat. No. 6,576,748, U.S. Pat. No. 6,646,111, U.S. Pat. No. 6,673,139,U.S. Pat. No. 6,958,406, U.S. Pat. No. 6,821,327, U.S. Pat. No.7,053,227, U.S. Pat. No. 7,381,831 and U.S. Pat. No. 7,427,323, thedisclosures of each of which are incorporated herein by reference intheir entirety.

In embodiments, solvent dyes are employed. An example of a solvent dyesuitable for use herein may include spirit soluble dyes because of theircompatibility with the ink carriers disclosed herein. Examples ofsuitable spirit solvent dyes include Neozapon Red 492 (BASF); Orasol RedG (Pylam Products); Direct Brilliant Pink B (Global Colors); AizenSpilon Red C-BH (Hodogaya Chemical); Kayanol Red 3BL (Nippon Kayaku);Spirit Fast Yellow 3G; Aizen Spilon Yellow C-GNH (Hodogaya Chemical);Cartasol Brilliant Yellow 4GF (Clariant); Pergasol Yellow 5RA EX(Classic Dyestuffs); Orasol Black RLI (BASF); Orasol Blue GN (PylamProducts); Savinyl Black RLS (Clariant); Morfast Black 101 (Rohm andHaas); Thermoplast Blue 670 (BASF); Savinyl Blue GLS (Sandoz); LuxolFast Blue MBSN (Pylam); Sevron Blue 5GMF (Classic Dyestuffs); BasacidBlue 750 (BASF); Keyplast Blue (Keystone Aniline Corporation); NeozaponBlack X51 (C.I. Solvent Black, C.I. 12195) (BASF); Sudan Blue 670 (C.I.61554) (BASF); Sudan Yellow 146 (C.I. 12700) (BASF); Sudan Red 462 (C.I.260501) (BASF), mixtures thereof and the like.

The colorant may be present in the phase change ink in any desired oreffective amount to obtain the desired color or hue such as, forexample, at least from about 0.1 percent by weight of the ink to about50 percent by weight of the ink, at least from about 0.2 percent byweight of the ink to about 20 percent by weight of the ink, and at leastfrom about 0.5 percent by weight of the ink to about 10 percent byweight of the ink.

In embodiments, in the molten state, the ink carriers for the phasechange inks may have a viscosity of from about 1 to about 22 cps, orfrom about 4 to about 15 cps, or from about 6 to about 12 cps, at a thejetting temperature. The jetting temperature is typically comprised in arange from about 100° C. to about 140° C. In embodiments, the solid inkhas a viscosity of about >10⁶ cps, at room temperature. In embodiments,the solid ink has a T_(melt) of from about 65 to about 140° C., or fromabout 70 to about 140° C., from about 80 to about 135° C. and a T_(crys)of from about 40 to about 140° C., or from about 45 to about 130° C.,from about 50 to about 120° C., as determined by DSC at a rate of 10°C./min.

The ink compositions can be prepared by any desired or suitable method.For example, each of the components of the ink carrier can be mixedtogether, followed by heating, the mixture to at least its meltingpoint, for example from about 60° C. to about 150° C., 80° C. to about145° C. and 85° C. to about 140° C. The colorant may be added before theink ingredients have been heated or after the ink ingredients have beenheated. When pigments are the selected colorants, the molten mixture maybe subjected to grinding in an attritor or ball mill apparatus or otherhigh energy mixing equipment to affect dispersion of the pigment in theink carrier. The heated mixture is then stirred for about 5 seconds toabout 30 minutes or more, to obtain a substantially homogeneous, uniformmelt, followed by cooling the ink to ambient temperature (typically fromabout 20° C. to about 25° C.). The inks are solid at ambienttemperature. In a specific embodiment, during the formation process, theinks in their molten state are poured into molds and then allowed tocool and solidify to form ink sticks. Suitable ink preparationtechniques are disclosed in U.S. Pat. No. 7,186,762, the disclosure ofwhich is incorporated herein by reference in its entirety.

The inks can be employed in apparatus for direct printing ink jetprocesses and in indirect (offset) printing ink jet applications.Another embodiment disclosed herein is directed to a process whichcomprises incorporating an ink as disclosed herein into an ink jetprinting apparatus, melting the ink, and causing droplets of the meltedink to be ejected in an imagewise pattern onto a recording substrate. Adirect printing process is also disclosed in, for example, U.S. Pat. No.5,195,430, the disclosure of which is totally incorporated herein byreference. Yet another embodiment disclosed herein is directed to aprocess which comprises incorporating an ink as disclosed herein into anink jet printing apparatus, melting the ink, causing droplets of themelted ink to be ejected in an imagewise pattern onto an intermediatetransfer member, and transferring the ink in the imagewise pattern fromthe intermediate transfer member to a final recording substrate. In aspecific embodiment, the intermediate transfer member is heated to atemperature above that of the final recording sheet and below that ofthe melted ink in the printing apparatus. In another specificembodiment, both the intermediate transfer member and the finalrecording sheet are heated; in this embodiment, both the intermediatetransfer member and the final recording sheet are heated to atemperature below that of the melted ink in the printing apparatus; inthis embodiment, the relative temperatures of the intermediate transfermember and the final recording sheet can be (1) the intermediatetransfer member is heated to a temperature above that of the finalrecording substrate and below that of the melted ink in the printingapparatus; (2) the final recording substrate is heated to a temperatureabove that of the intermediate transfer member and below that of themelted ink in the printing apparatus; or (3) the intermediate transfermember and the final recording sheet are heated to approximately thesame temperature. An offset or indirect printing process is alsodisclosed in, for example, U.S. Pat. No. 5,389,958, the disclosure ofwhich is totally incorporated herein by reference. In one specificembodiment, the printing apparatus employs a piezoelectric printingprocess wherein droplets of the ink are caused to be ejected inimagewise pattern by oscillations of piezoelectric vibrating elements.Inks as disclosed herein can also be employed in other hot melt printingprocesses, such as hot melt acoustic ink jet printing, hot melt thermalink jet printing, hot melt continuous stream or deflection ink jetprinting, and the like. Phase change inks as disclosed herein can alsobe used in printing processes other than hot melt ink jet printingprocesses.

Such robust inks may be used with printing equipment at high speeds.Typically, production digital presses print at a speed comprised fromabout 100 to 500 or more feet/minute. This requires inks which arecapable of solidifying very fast once placed onto the paper, in order toprevent offset of the printed image during fast printing process, whereprinted paper is either stacked (cut-sheet printers) or rolled(continuous feed printers). Fast crystallization is not a general orinherent property of crystalline-amorphous robust inks. Therefore notall crystalline-amorphous inks are suitable for fast printing. Thepresent inventors have discovered specific crystalline amide compoundswhich when used in conjunction with specific amorphous compounds providefast crystallization, therefore enabling fast printing.

In order to evaluate the suitability of a test ink for fast printing aquantitative method for measuring the rates of crystallization of phasechange inks containing crystalline components was developed. TROM(Time-Resolved Optical Microscopy) enables comparison between varioustest samples and, as a result, is a useful tool for monitoring theprogress made with respect to the design of fast crystallizing inks.

TROM is described in co-pending U.S. patent application Ser. No. ______(not yet assigned) entitled “TROM Process for Measuring the Rate ofCrystallization of Phase change Inks” to Gabriel Iftime et al.,electronically filed on the same day herewith (Attorney Docket No.20110828-401275).

Time Resolved Optical Microscopy (TROM) monitors the appearance and thegrowth of crystals by using Polarized Optical Microscopy (POM). Thesample is placed between crossed polarizers of the microscope.Crystalline materials are visible because they are birefringent.Amorphous materials or liquids, similar to, for example, inks in theirmolten state that do not transmit light, appear black under POM. Thus,POM enables an image contrast when viewing crystalline components andallows for pursuing crystallization kinetics of crystalline-amorphousinks when cooled from the molten state to a set-temperature. Polarizedoptical microscopy (POM) enables exceptional image contrast when viewingcrystalline components.

In order to obtain data that allow comparison between different andvarious samples, standardized TROM experimental conditions were set,with the goal of including as many parameters relevant to the actualprinting process. The ink or ink base is sandwiched between 16-25 mmcircular thin glass slides of a thickness of 0.2 mm to 0.5 mm. Thethickness of the ink layer is kept at 5-25 μm (controlled withfiberglass spacers) which is close to actual printed ink layers. Forrate of crystallization measurement, the sample is heated to theexpected jetting temperature (viscosity of about 10-12 cps) via anoffline hotplate and then transferred to a cooling stage coupled with anoptical microscope. The cooling stage is thermostated at a presettemperature which is maintained by controlled supply of heat and liquidnitrogen. This experimental set-up models the expected drum/papertemperature onto which a drop of ink would be jetted in real printingprocess (40° C. for the experiments reported in this disclosure).Crystal formation and growth is recorded with a camera.

The key steps in the TROM process are illustrated in FIG. 2,highlighting the key steps in the measuring process with the mainlineink base which contains just amorphous and crystalline components (nodye or pigment). When viewed under POM, the molten and at time zero, thecrystalline-amorphous inks appear black as no light is passed through.As the sample crystallizes, the crystalline areas appear brighter. Thenumbers reported by TROM include: the time from the first crystal(crystallization onset) to the last (crystallization completion).

The definition of key measured parameters of the TROM process are setforth below:

-   -   Time zero (T=0 s)−the molten sample is placed on the cooling        stage under microscope    -   T onset=the time when the first crystal appears    -   T growth=the duration of the crystal growth from the first        crystal (T onset) to the completion of the crystallization (T        total)    -   T total=T onset+T growth

It should be understood that the crystallization times obtained with theTROM method for selected inks are not identical to what would be thecrystallization times of a droplet of ink in an actual printing device.In an actual printing device such as a printer, the ink solidifies muchfaster. We determined that there is a good correlation between the totalcrystallization time as measured by the TROM method and thesolidification time of an ink in a printer. In the standardizedconditions described above, we determined that inks solidify within10-15 seconds or less measured by the TROM method, are suitable for fastprinting, typically at speeds from 100 feet/minute or higher. Therefore,for the purpose of the present disclosure, a rate of crystallizationlower than 15 seconds, is considered to be fast crystallizing.

In certain embodiments, the phase change ink crystallizes in less than15 seconds.

Any suitable substrate or recording sheet can be employed, includingcoated and plain paper. Coated paper includes silica coated papers suchas Sharp Company silica coated paper, JuJo paper, HAMMERMILL LASERPRINTpaper, and the like, glossy coated papers such as XEROX Digital ColorElite Gloss, Sappi Warren Papers LUSTROGLOSS, specialty papers such asXerox DURAPAPER, and the like. Plain paper includes such as XEROX 4200papers, XEROX Image Series papers, Courtland 4024 DP paper, rulednotebook paper, bond paper. Transparency materials, fabrics, textileproducts, plastics, polymeric films, inorganic recording mediums such asmetals and wood, may also be used.

The inks described herein are further illustrated in the followingexamples. All parts and percentages are by weight unless otherwiseindicated.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also,various presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art, and are also intended to beencompassed by the following claims.

While the description above refers to particular embodiments, it will beunderstood that many modifications may be made without departing fromthe spirit thereof. The accompanying claims are intended to cover suchmodifications as would fall within the true scope and spirit ofembodiments herein.

The presently disclosed embodiments are, therefore, to be considered inall respects as illustrative and not restrictive, the scope ofembodiments being indicated by the appended claims rather than theforegoing description. All changes that come within the meaning of andrange of equivalency of the claims are intended to be embraced therein.

EXAMPLES

The examples set forth herein below and are illustrative of differentcompositions and conditions that can be used in practicing the presentembodiments. All proportions are by weight unless otherwise indicated.It will be apparent, however, that the present embodiments can bepracticed with many types of compositions and can have many differentuses in accordance with the disclosure above and as pointed outhereinafter.

Example 1 Preparation of Ink Samples

DMT shown in U.S. patent application Ser. No. 13/095,784 was used as theamorphous compound in the ink. Combinations of each crystalline compound(1.6 grams) shown in Table 1 and DMT (0.4 grams) were stirred in themolten state at 140° C. without dye, then cooled down to obtain the inkbase samples. The crystalline:amorphous ratio of the ink samples were80:20 in weight percent. The crystalline and amorphous materials werewell-miscible in this mixing ratio. The formulations are shown in Table2 below.

TABLE 2 Ink Formulation (wt %) Amide Amide Amide Solvent T_(melt)T_(crys) Ink ID No. 1 No. 2 No. 3 DMT Blue 101 (° C.)* (° C.)* Ink 80 2093 53 Base 1 Ink 80 20 110 84 Base 2 Sample 78.4 19.6 2 111 81 Ink 1(made from Ink Base 2) *T_(melt) = melt ng temperature, T_(crys) =crystallization temperature (determined by DSC at a rate of 10° C./min).

Among the three ink samples, Ink Base 2 (containing Amide No. 2N-phenethylbenzamide) was identified as providing the most desirableformulation based on DSC data analysis, as shown in FIG. 3 and Table 2.

FIG. 2 shows that Ink Base 2 melted at about 110° C. (T_(melt)) andshowed relatively sharp crystallization peak at about 84° C. (T_(crys)).Both temperatures were within the desired range and ΔT(=T_(melt)−T_(crys)) was also small.

Because of the desirable thermal properties, the formulation ratio ofInk Base 2 was used to make Sample Ink 1 by adding 2 wt % Solvent Blue101 dye (commercially available from Keystone (Chicago, Ill.)) (inkformulation: Crystalline/Amorphous/Dye=67.9/29.1/3 (wt %)=2.72/1.16/0.12(g)). FIG. 4 shows DSC data of Sample Ink 1. Both T_(melt) and T_(crys)were little affected, and the sample still showed remarkably sharp phasetransitions, even when blended with the dye.

Rheological Properties

FIG. 5 shows the rheology data of Ink Base 2 and Sample Ink 1. The inksexhibited phase transition to >10⁶ cps at about 110° C. The phasetransition temperature will be adjustable by selection of materials andchanging the crystalline/amorphous ratio within the desirabletemperature range (65° C.<T<130° C.). Furthermore, the viscosity abovephase transition temperatures were below 10 cps and again adjustable bychanging the ratio or blending additives such as a viscosity modifier.

Ink Characterization

Comparative data for Ink Base 2 and Sample Ink 1 were obtained forcrystallization and are shown in Table 3 below. Rate of crystallizationwas measured by Time-Resolved Optical Microscopy (TROM) procedure.

The data demonstrates that the rates of crystallization weresufficiently fast and not significantly influenced by the presence ofdye. Printing tests performed with known inks on high speed printersdemonstrated correlation between the rate of crystallization measured byTROM and the solidifying time on the printer. One commercially availableink (Commercial Ink 1) achieved 4 sec crystallization time by TROM andsolidifies sufficiently fast when printed with a high speed printer. Onthe other hand, a competitive ink, also commercially available, whichcrystallizes in about 25 s in the TROM test was demonstrated to solidifytoo slowly when printing with the high speed printers on paper. Based onthis preliminary data, the expectation is that the ideal ink suitablefor fast printing should have a crystallization rate on TROM lower than15 seconds. As can be seen from Table 3, the inks of the presentembodiments achieve the desired rate, demonstrating suitability for fastprinting.

TABLE 3 Time Time crys T test crys elapsed Time crys Ink ID (° C.) onset(s) (s) total (s) Ink Base 2 120 2 10 12 Sample Ink 1 120 3 10 13

Sample Ink 1 was used for K-proof print test examination on coated paper(DCEG: Xerox digital Color Elite Gloss, 120gsm). A K-proofer(manufactured by RK Print Coat Instrument Ltd., Litlington, Royston,Heris, SG8 00Z, U.K.) is a common test fixture in a print shop. In thiscase the K-proofer has been modified to heat the printing plate to meltthe phase change ink. The K-Proofer used has three rectangular gravurepatterns each approximately 9.4×4.7 cm. The cell density of the firstrectangle is nominally 100%, the second 80%, and the third 60%. Inpractice this K-proof plate results in films (or pixels) of about 5microns in thickness (or height). Test ink is spread over the heatedgravure plate and a test print is made by passing a wiping blade acrossthe plate surface immediately followed by a rubber roll upon which atest paper has been secured. As the paper roll passes ink is transferredfrom the gravure cells to the paper.

When a scratch/gouge finger with a curved tip at an angle of about 15°from vertical, with a weight of 528 g applied, was drawn across theimage at a rate of approximately 13 mm/s, no ink was visibly removedfrom the image. The scratch/gouge tip is similar to a lathe round nosecutting bit with radius of curvature of approximately 12 mm.

The claims, as originally presented and as they may be amended,encompass variations, alternatives, modifications, improvements,equivalents, and substantial equivalents of the embodiments andteachings disclosed herein, including those that are presentlyunforeseen or unappreciated, and that, for example, may arise fromapplicants/patentees and others. Unless specifically recited in a claim,steps or components of claims should not be implied or imported from thespecification or any other claims as to any particular order, number,position, size, shape, angle, color, or material.

All the patents and applications referred to herein are herebyspecifically, and totally incorporated herein by reference in theirentirety in the instant specification.

1. A phase change ink comprising: an amorphous compound; and acrystalline compound being an amide having a formula of:

wherein each R₃ and R₄ is independently selected from the groupconsisting of (i) an arylalkyl group, wherein the arylalkyl group isoptionally substituted, wherein the alkyl portion of the arylalkyl groupis optionally linear or branched, cyclic or acyclic, substituted orunsubstituted, saturated or unsaturated, and further wherein heteroatomsis optionally present in either the aryl portion or the alkyl portion ofthe arylalkyl group having from 4 to 40 carbon atoms, (ii) an aromaticgroup, wherein the aromatic group is optionally substituted, wherein thesubstituent is optionally a linear, branched, cyclic or acyclic alkylgroup and further wherein heteroatoms is optionally present in thearomatic group having from 3 to 40 carbon atoms, and mixtures thereof;and wherein the phase change ink crystallizes in less than 15 seconds.2. The phase change ink of claim 1, wherein the amorphous compoundcomprises an ester of tartaric acid of Formula I

wherein each R₁ and R₂ is independently an alkyl group, wherein thealkyl can be straight, branched or cyclic, saturated or unsaturated,substituted or unsubstituted, having from 1 to 40 carbon atoms, or ansubstituted or unsubstituted aromatic or heteroaromatic group, andmixtures thereof.
 3. The phase change ink of claim 2, wherein thetartaric acid backbone is selected from L-(+)-tartaric acid,D-(−)-tartaric acid, DL-tartaric acid, or mesotartaric acid, andmixtures thereof.
 4. The phase change ink of claim 3, wherein theamorphous compound is present in an amount of from about 5 percent toabout 35 percent by weight of the total weight of the phase change ink.5. The phase change ink of claim 1, wherein the crystalline compound ispresent in an amount of from 60 percent to 95 percent by weight of thetotal weight of the phase change ink.
 6. The phase change ink of claim1, wherein the crystalline compound of Formula II has a meltingtemperature (T_(melt)) of less than 150° C. and a crystallizationtemperature (T_(crys)) of greater than 60° C.
 7. The phase change ink ofclaim 1 further comprising a colorant selected from the group consistingof a pigment, dye or mixtures thereof.
 8. The phase change ink of claim1, wherein the crystalline compound has a viscosity of less than 10 cpsat a temperature of 140° C.
 9. The phase change ink of claim 1, whereinthe crystalline compound has a viscosity of greater than 10⁶ cps at roomtemperature.
 10. The phase change ink of claim 1, wherein the amorphouscompound has a viscosity of from about 1 to about 100 cps at atemperature of 140° C.
 11. The phase change ink of claim 1, wherein theamorphous compound has a viscosity of greater than 10⁵ cps at roomtemperature.
 12. The phase change ink of claim 1 having a viscosity offrom 1 to 22 cps in a jetting range from about 100° C. to about 140° C.13. The phase change ink of claim 12 having a viscosity of from 4 to 15cps in a jetting range from about 100° C. to about 140° C.
 14. The phasechange ink of claim 1 having a viscosity of greater than 10⁶ cps at roomtemperature.
 15. A phase change ink comprising: an amorphous compoundcomprises an ester of tartaric acid of Formula I

wherein each R₁ and R₂ is independently an alkyl group, wherein thealkyl can be straight, branched or cyclic, saturated or unsaturated,substituted or unsubstituted, having from 1 to 40 carbon atoms, or ansubstituted or unsubstituted aromatic or heteroaromatic group, andmixtures thereof; and further wherein the tartaric acid backbone isselected from L-(+)-tartaric acid, D-(−)-tartaric acid, DL-tartaricacid, or mesotartaric acid, and mixtures thereof; and a crystallinecompound being an amide having the following structure:

wherein each R₃ and R₄ is independently selected from the groupconsisting of (i) an arylalkyl group, which can be a wherein thearylalkyl group is optionally substituted, wherein the alkyl portion ofthe arylalkyl group is optionally linear or branched, cyclic or acyclic,substituted or unsubstituted, saturated or unsaturated, and furtherwherein heteroatoms is optionally present in either the aryl portion orthe alkyl portion of the arylalkyl group having from 4 to 40 carbonatoms, (ii) an aromatic group, wherein the aromatic group is optionallysubstituted, wherein the substituent is optionally a linear, branched,cyclic or acyclic alkyl group, and further wherein heteroatoms isoptionally present in the aromatic group having from 3 to 40 carbonatoms, and mixtures thereof; and further wherein the phase change inkhas a T_(melt) of from 65 to 140° C. and a T_(crys) of from 40 to 140°C.
 16. A phase change ink comprising: an amorphous compound; and acrystalline compound, wherein the amorphous compound is an ester oftartaric acid and is synthesized by an esterification reaction with atleast one alcohol, and the crystalline compound is an amide having thefollowing structure:

wherein each R₅ and R₆ is independently aryl, or heteroaryl, optionallysubstituted with one or more alkyl, alkoxy, —NH₂, —CN, or —OH; m is from0 to 6, n is from 0 to
 6. 17. The phase change ink of claim 16, whereinR₅ and R₆ is independently phenyl or naphthyl, optionally substitutedwith one or more methyl, ethyl, methoxy, ethoxy, —NH₂, —CN, or —OH. 18.The phase change ink of claim 16, wherein the amide is selected from thegroup consisting of N-phenethylhydrocinnamide, N-phenethylbenzamide, andN-benzylbenzamide, and mixtures thereof.
 19. The phase change ink ofclaim 16, wherein the alcohol is selected from the group consisting ofmenthol, isomenthol, neomenthol, isoneomenthol, and any stereoisomersand mixtures thereof.
 20. The phase change ink of claim 16, wherein thephase change ink crystallizes in less than 15 seconds.